1. Field of the Invention
The present invention relates to a retractable vehicle seat of laterally folding type, which is basically composed of a seat cushion and a seat back and allows the seat to be folded in a lateral direction of vehicle relative to a support arm fixed on one lateral side of the vehicle, so that a user can fold down the seat from a non-use storage position where it is to be located on one lateral side of vehicle, in a direction to a use position where it is to be located inwardly of the vehicle to supportively receive the user thereon, and that the user can also retract the seat at that use position back to the afore-said non-use storage position. In particular, the invention is directed to a powered retractable vehicle seat of this kind which has an electric motor as a drive source to cause such lateral folding of seat between the non-use storage and use positions relative to the support arm.
2. Description of Prior Art
There has been known a retractable seat of laterally folding type for use in a vehicle. This sort of seat is typically used as a rear seat, and particularly used as a third seat in a relatively large vehicle such as station wagons, vans and various multipurpose cars. As stated above, the seat is foldable in a direction laterally of a vehicle and normally set in a non-use storage position where it is disposed adjacent to one lateral side of the vehicle, thereby normally providing a wide space or an enlarged load-carrying platform in the rearward portion of the vehicle. A user can manually fold down the seat from that non-use storage position to a horizontal use position where it extends horizontally from one lateral side of vehicle, thereby providing an extra seat on which the user can sit. Of course, when in no use, the user can tip up the seat from that use position and retract it to the non-use storage position on one lateral side of vehicle. Hence, this sort of retractable seat is of the so-called “laterally folding type” and has been disclosed for instance from the Japanese Laid-Open Patent Publication No. 9-193699.
Also, known is a powered type of such laterally folding seat which has a motor operatively connected with a seat, such that the motor is electrically operated to cause the seat to displace laterally of vehicle towards a selected one of the non-use storage position and use position as mentioned above. This powered type is disclosed from the Japanese Laid-Open Patent Publication No. 5-170021 (hereinafter, “JPB '021”) for example.
According to the JPB '021, a seat is operatively connected, via motor and lead screw mechanism, with a bracket provided on a slide rail device which is disposed at one lateral side of vehicle. Specifically, a seat cushion of the seat is pivotally connected with the said bracket, and a lead screw is movably connected between the seat cushion and the slide rail, with a gear box provided with the motor being threadedly engaged about that lead screw (i.e. the gear box includes a nut threadedly engaged about the lead screw). The gear box is pivotally connected with a lateral side of the seat cushion which faces to the slide rail device. Operation of the motor results in both of the gear box and motor translating on and along the longitudinal direction of the lead screw in either of seat use direction and seat non-use direction. That is, operating the motor in the seat use direction causes movement of the gear box along the lead screw in a direction inwardly of the seat cushion, thereby causing the seat to fold down from the non-use storage position to the horizontal use position. Conversely, operating the motor in the seat non-use direction causes movement of the gear box along the lead screw in a direction outwardly of the seat cushion, thereby causing the seat to tip up or retract from the use position to the non-use storage position.
However, the JPB '021 has been found defective in that:
(i) Both gear box and motor are free to rotate via link with respect to the seat cushion, which means that a vibration during running of vehicle causes undesired movement of those gear box and motor, with the result that the motor itself generates an undesired rattling which will give an unpleasant noise to a seat occupant.
(ii) During operation, a load from the seat is directly exerted on the lead screw, and therefore, it is required that the lead screw and a pin which pivotally supports the lead screw should be provided with an increased rigidity enough to withstand such load applied from the seat, by increasing a thickness of each of those two elements and adding a reinforcing element thereto. As a result thereof, a whole structure of seat becomes great in weight and size and also becomes complicated.
(iii) A free end portion of the lead screw extends in a direction transversely of seat cushion, which requires formation of a hollow or storage portion in the seat cushion to house such free end portion. This will adversely deform the shape and thickness of the seat cushion and deteriorate the cushiony touch thereof.